Protective device for motor controllers and starters.



A.' I.. .OUNL PROTECTIVE DEVICE FDR'II'IOTOR CONTROLLERS AND STARTERS. APPLICATION FILED IMI. 8, ISI?.

LEI. Tatented '26, IIIIh',

lQ3 and 211 being which, when the and 4 or other source of supply, the coils interposed reapeci'ively in. the opposite .sidesy of the control circuiti. (lne of the eonolnetonl 25 for the Control circuit extends to the coil Q3 and thence by a series of .branch conductors 26 to the coil of the magnet: 9 and the solenoid eoilb` 15 and 16. The other main conductor 2T( of the. auxiliary or control Circuit extends through the eoil 2-1 of the protective dii'erential relay and thenceby a Series of branch conductors 28 to the switches 1? and 18 and to one of the contacts 20. The other Contact 20 is connected to the eoil of the Switch 9 by a conductor 29 and the contacts of the switches 17 and 18 are vconnected respee tively hy conductors 30 and 31 to the solenoid coils-15 and 16.

1n the arrangement shown the protective relay is provided with an armature heving a finger 33 thereon whieh engages lille insulated end ot' a spring-held switch 34e and normally holds the latter in open position. This switch and its Contact are eonnested reopeetively to Conductors 35 and 3G Switeh is closed, forms a shunt around theI coil or' the magnet 9. `Whon the armature is shifted. this shunt is elosed and the Switch i) is thas prevented 'from closing or, if Closed1 is opened. ,lreernbly also, the movement ot the armature 32 is arranged to close :1 eirenit, through a Signal lamp 37 which, in the arrangement; shown, is interposed in a Conductor B8 that leads 1"om the, conductor 4 to the normally open eontaet of'the armature switeh 32. The latter is eonneeted to eondnetor 3 by a eondnetor 39.

ln the normal operation of the Controlling' system, :ifter the switeh 5 is Closed to eonneet. the supply eondnetors 1 :ind 2 to the conductors 3 :1nd -l of the motor eirrrnit, the inotor ma;V he started hy elosing the, switch 1S so thatJ a enrreniy flows from eendnetor 3 hy the eondnetor 25. the eoil 23 oi the differential relay, one ot' the ln'aneh eontlnetors 26 to the solenoid roil 16, thenee hy conductor 31, switch 18, lpraneh eondm'ior Ql the. other eoil 24 nl the differential' relay and eondnetor Q7 to the oppoeite eirenit. eon- (lnetor 1. The switeh l() in thus shifted hy the solenoid eoil 16 to bridge the eontaets 1Q and 13 and elose the eontzlets Q0. When fthe eomaets Qt) are closed, the rnrrent will ow from eontlnetor 3 hy eondnrtor Q5', eoil 23, one oi the lnanr'h r'ondneiors Q6. eoil of switeh il. eondnetor Q5). eontarts Q0, eondnetor 2R, eoil 24 and eonflnetor Q7 to mein oondnetor 4. The eoil of Siviteh il is thus energized and bridging switeh l) elosed. lhe, switehes 19 und 10 thus close the motor eirfnit. and hv holding the .Qwieh 19 elosed. or momentaril)r elosing' ii. from time to time. the switch 1() van he moved along mer the emitan-ts 13 to ,gradually reilnee the nmonnl.

of the resistance motor eirenit; and thereby increase the amount. of: current flowing in the motor eircni and 'the speed of the motor. The speed of 'the meier n'iay oleo be reduced from {inie to time desired or the motor circuit. oieiened by operating the i Y ential relay 2:2 are so wound tenet their no tion npon the-protective member or armutnre 32 is normali",v baleneeil and since the auxiliary circuit is closed throng-h both of these coils wheneve any one of the Switches therein is closed. the. armatore 32 will ro main et rest during the, normal operation of the controliinffj system. But if the control eireuit is areidentall rounded on either Side, the enrrent vaine anpiiecl tao one of the eoilfl; will exceed that in the opposed coil so that, 'the action, or the emile; balanretl and the armati from the position s iown. thereby' releasing the switch '-land e Circuit of the. signal lamp il?. mi

i ne swiali 31. 21S (leseriiied, will then eloS-e the slnml, around 'the coil of the magnet Switeh 9, no that. the main motor eirenit. it elose'ffl. is liroken ai' this; point or if open, is prevented from elosingij. With the ni. ti'ii tion shown, "when the armature 82 is shifted to release the switrh 31: latter will remain eloneii eren though the former it; retoretl 'to normal, and the eontrol System en nno; he restored to normal rendition nn'il he witeh is opened by hand or other-WiSe. deeireri, 'the safely deviee or armature may he :rranfyeff to operate other means wliieh wonlol pirsere'nt damage h V the :ieeidentel grounding; of the Ponti-ol eireuit. Y

'i the arrangei'nent Shown in 15. S15 ai hreephase alternaiine' wirr/"i1, motor il? iS supplied with ein-rent hf: three phone i dnetoi-S il1, 1Q nml '-13. AThe efnnlneor fifi io ronneeted direetly lo the motor and the eondnetors and L13 ieee respeetiveiy through lie ronine; @fr ind ffi of switch 16. r1`he latter is actuated hy n solenoid Coil 1,7 interpoed in :in miifiliory or' control eir enii whieh inelndes n eeriing si'vieli 48. When the starting swiii eliiet? gage its eontaet the, e the phase conductor or n eondiietor 51 through one of the oyrgieQe-il eoiis of the rev :30. thenee hy eondnetor i231 solenoid f eondnelor 5l, .Qvf'iteli 1150. eontlnfit through the opgiofsii ,e eoii o'l' iie 'rel I i'lienre hy l'ie eondiieoi 5G to the 'g i dnetor fifi. rl-"he eoii fr? is f elosle, the mein motor voila of t?" l "n ,re le) litre swifls D' the' closed position. A ground on the control circuit will, however, unbalance the coils of the relay'O, actuate the switch 49 and close a shunt through the conductors 53 and 54 around the solenoid coil 47 and thus stop auxiliary circuit anda control switch therein for controlling said electro-magnetic switch, a differential relay having normall balanced coils interposed respectively-in t e opposite sides of said control circuit between the source of supply therefor and said con- /trolled switch, and a protective switch arranged to be actuated by said relay when the coils thereof are unbalanced. A

2. The combination with Va motor and a motor circuit, of an auxiliary circuit for controlling said motor circuit, one or more control switches vin said auxiliary circuit, a ground ydetector comprising normally balanced coils interposed respectively in the oposite sides of said auxiliary control circuit etween the source of supply therefor and said controlled switch or switches, and means arranged to beactuated 'by said coils when unbalanced for protecting the main motor circuit. i

3. The combinationywith a motor and a motor' circuit, of an electroniagnetic switch in said motor circuit, an auxiliary circuit for controlling said electro-magnetic switch, one or more control mally balanced coils interposed res ectively in the opposite sides of said auxiliary control circuit adjacent the source of supply therefor, and a signal arranged to be actuated by said coils when unbalanced.

4. The combination with a motor and a mainsupply circuit therefor, of an electromagnetic switch in said supply circuit., an

` switches in said auxiliary circuit, a ground detector comprising norauxiliary circuit and a switch therein for controlling said electro-magnetic switch, af

protective differential relay having normally balanced coils interposed respectively in the vopposite sides of said coil circuit between the source of supply therefonand said control switch, and means controlled by said relay for preventing the operation of said electro-magnetic switch.'

5. The combination with a motor and the main supply circuit therefor, of ane1ectromagnetic switch in said supply circuit, an,

auxiliary circuit for operating said electromagnetic switch to open and close said main supply circuit, one or more control switches in said auxiliary circuit, a rotective diiereiital relay having normal y balanced coils interposed respectively in the opposite sides of said control circuit-'adjacent the source ot supply therefor, and neansfactuated by said relay when the coils thereof are unbalanced for preventing the closing of said electromagnetic switch.

ALLAN J. CLINE. 

